The Robust Lamina Cribrosa Vasculature: Perfusion and Oxygenation Under Elevated Intraocular Pressure.
Lu Yuankai, Hua Yi, Wang Bingrui, Zhong Fuqiang, Theophanous Andrew, Tahir Shaharoz, Lee Po-Yi, Sigal Ian A
AI Summary
This study simulated lamina cribrosa vessel collapse under high eye pressure. It found blood flow was sensitive to distributed collapse, while oxygenation was robust to it but vulnerable to clustered collapse.
Abstract
Purpose
Elevated intraocular pressure (IOP) is thought to cause lamina cribrosa (LC) blood vessel distortions and potentially collapse, adversely affecting LC hemodynamics, reducing oxygenation, and triggering, or contributing to, glaucomatous neuropathy. We assessed the robustness of LC perfusion and oxygenation to vessel collapses.
Methods
From histology, we reconstructed three-dimensional eye-specific LC vessel networks of two healthy monkey eyes. We used numerical simulations to estimate LC perfusion and from this the oxygenation. We then evaluated the effects of collapsing a fraction of LC vessels (0%-36%). The collapsed vessels were selected through three scenarios: stochastic (collapse randomly), systematic (collapse strictly by the magnitude of local experimentally determined IOP-induced compression), and mixed (a combination of stochastic and systematic).
Results
LC blood flow decreased linearly as vessels collapsed-faster for stochastic and mixed scenarios and slower for the systematic one. LC regions suffering severe hypoxia (oxygen <8 mm Hg) increased proportionally to the collapsed vessels in the systematic scenario. For the stochastic and mixed scenarios, severe hypoxia did not occur until 15% of vessels collapsed. Some LC regions had higher perfusion and oxygenation as vessels collapsed elsewhere. Some severely hypoxic regions maintained normal blood flow. Results were equivalent for both networks and patterns of experimental IOP-induced compression.
Conclusions
LC blood flow was sensitive to distributed vessel collapses (stochastic and mixed) and moderately vulnerable to clustered collapses (systematic). Conversely, LC oxygenation was robust to distributed vessel collapses and sensitive to clustered collapses. Locally normal flow does not imply adequate oxygenation. The actual nature of IOP-induced vessel collapse remains unknown.
MeSH Terms
Shields Classification
Key Concepts6
In numerical simulations using reconstructed three-dimensional eye-specific lamina cribrosa (LC) vessel networks from two healthy monkey eyes, LC blood flow decreased linearly as vessels collapsed, with faster decreases for stochastic and mixed scenarios of vessel collapse and slower for the systematic scenario.
In numerical simulations using reconstructed three-dimensional eye-specific lamina cribrosa (LC) vessel networks from two healthy monkey eyes, LC regions suffering severe hypoxia (oxygen <8 mm Hg) increased proportionally to the collapsed vessels in the systematic scenario of vessel collapse.
In numerical simulations using reconstructed three-dimensional eye-specific lamina cribrosa (LC) vessel networks from two healthy monkey eyes, for the stochastic and mixed scenarios of vessel collapse, severe hypoxia (oxygen <8 mm Hg) did not occur until 15% of vessels collapsed.
In numerical simulations using reconstructed three-dimensional eye-specific lamina cribrosa (LC) vessel networks from two healthy monkey eyes, LC blood flow was sensitive to distributed vessel collapses (stochastic and mixed scenarios) and moderately vulnerable to clustered collapses (systematic scenario).
In numerical simulations using reconstructed three-dimensional eye-specific lamina cribrosa (LC) vessel networks from two healthy monkey eyes, LC oxygenation was robust to distributed vessel collapses and sensitive to clustered collapses.
In numerical simulations using reconstructed three-dimensional eye-specific lamina cribrosa (LC) vessel networks from two healthy monkey eyes, locally normal blood flow does not imply adequate oxygenation.
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